A prominent Uighur academic charged with separatism has rejected evidence presented by Chinese prosecutors on the first day of a trial that has drawn criticism from international judicial and human rights activists.

Ilham Tohti, an economics professor in Beijing, went on trial in China's Xinjiang region on Wednesday on charges of promoting independence for the minority Muslim Uighurs, serious allegations that carry the maximum penalty of death.

China hopes that it can threaten Uighur intellectuals of conscience to accept and spread China's policies of enslavement.

Dilxat Raxit, World Uyghur Congress

Prosecutors "essentially finished" presenting evidence against Tohti, including testimony from his former students, his lawyer, Li Fangping said, rejecting it as made under duress.

"We believe they weren't trustworthy statements, that they were made under pressure," Li told Reuters news agency by phone, adding that Tohti refused to accept the testimony.

Seven of Tohti's students, who had worked on a Uighur-language website he managed, were also detained after his January 15 detention in Beijing.

Tohti and his student were sent to Urumqi, despite his lawyers' petitions to have the trial transferred to Beijing where he lived and worked.

On Wednesday, police set up a two-block cordon around the court in Urumqi and blocked access to reporters and a group of at least nine Western diplomats who sought to observe the trial, one diplomat said by telephone.

A photo obtained by Reuters of the scene near the courthouse showed police with riot shields and batons setting up six-foot tall poster-like barricades with phrases invoking "openness" and "unity".

"Let the world understand Xinjiang, let Xinjiang go out to the world," one of the posters read.

Crackdown on dissent

Tohti's case, which has attracted high-level concern in the United States and the European Union, is seen as an extension of a government crackdown on dissent in Xinjiang, where tension between Uighurs and majority Han Chinese has led to violence.

Beijing has blamed a series of violent attack in Xinjiang and around the country on armed groups, who it said wanted to establish an independent state called East Turkestan, and had carried out several executions in recent months.

The Uighurs: External Exile

Tohti, who taught at Beijing's Minzu University, which specialises in ethnic minority studies, has said he never associated with any "terrorist" organisation or foreign-based group, and has "relied only on pen and paper to diplomatically request" human rights and legal rights for Uighurs.

China said "extremist groups" in bordering south and central Asian countries are spurring the violence in Xinjiang and around China, though the government has produced little evidence and experts question the extent of the links.

Human Rights Watch has called the trial a "travesty of justice" and the exiled World Uyghur Congress said his prosecution would only intensify ethnic conflict.

"China hopes that by charging Ilham Tohti it can threaten Uighur intellectuals of conscience to accept and spread China's policies of enslavement," Dilxat Raxit, spokesman for the group, said in an emailed statement.